Getting the "knock"

Harrogate Velo50

Hi guys

Bit of advice if possible please. On a couple of rides,( yesterday 70miles and flat, and one 45 miles with 4.5k feet of climbing) I have suffered the dreaded knock.

Now on neither ride have I really tried to smash it at all (pushed it a bit on the 70miler but not much) but both tines in last 10 miles I have really hit the wall, which is unusual and not very nice

I feel that have fuelled correctly before (porridge with honey and granola and a bagel) and fuelled on the ride(Clif bar, flap Jack, a gel, bannana and one coffee and fruit cake on the 70mile)

Thought would be enough but proved otherwise as I felt bloody awful last few miles.

Riding conditions were very good, certainly on the 70 miler. I am 52, five foot 7 and I think bout 9stone 12.

Appreciate it's all quite vague info, but any thoughts or advice would really appreciate. I'm quite used to doing the above distances etc so it's bit of a surprise that it has happened twice in last month

Many thanks

kajjal

It is a lot harder going in winter than summer which may contribute. My Sunday ride was very hard work due to it being wet and very cold. Other things are more life style based like diet, resting enough, stress, existing medical conditions etc.

You may just have been unlucky.

AK_jnr

Or you just aren't yet at the fitness level you have been in the past?

diy

There are lots of bugs around + winter riding is harder work even just the extra effort pushing legs with long trousers vs bib shorts makes a difference. If you are consistently hitting the wall you could try a bit of endurance training to up your efficiency, or even low cal training on a regular basis, but winter is no time to be doing anything other than riding as much as you can weather permitting.

Did you try a gel? if you can perk yourself up with a gel, then it could be fuel otherwise its just winter riding.

Harrogate Velo50

I did have one gel yes, and I would think my fitness it maybe a bit better than it was.

As soon as I had finished I had peanut sandwich and sweet potato with beans and felt much better quite quickly, so guess another question is what sort of foods should I be taking on board to help? Felt I had eaten enough but maybe not. Another thing just realised is that I drunk just one bottle and a glass of water on the 70miles :oops:

diy

Its so hard on longer rides to force yourself to take on fluid and food, generally I find I have to push myself to take on more than I feel like.

Making the water "tasty" helps. You don't really need anything beyond sugar and salt. I certainly noticed an improvement on endurance rides, switching from just water. Could all be in the mind though.

tangled_metal

It's amazing how quickly it can happen. You're happily cycling/running/walking along and you suddenly go from decent energy to no energy and a real struggle.

I used to do challenge walks over up to 50 miles and nutrition was my achilles heel. When working hard I could never get enough through into my system. With high sugar content foods I found I got a sudden energy but then dipped. For me that was down to the sudden high blood sugar level triggering the insulin response which pushes it all the other way and I get a sugar low. Take another gel or sugary snack and it happens again.

Walking is not cycling (even at the pace I walked) but the same mechanism could happen in you case. Perhaps try not to eat the whole energy bar but nibble a bit then a bit more. Try to spread it out a bit. Or perhaps intermingle the energy bars / gels with more natural foods perhaps with a bit of fats in there. IME preventing the sugar high does wonders, especially if the workout is not a high intensity one. If it is slow and steady then copy that with the food I guess.

Now don't get me onto porridge! Everyone thinks it is some kind of wonderful breakfast food, but whenever I have had it I am hungry and hitting the wall within 1-02 hours of eating a great big bowl of porridge and honey. I am talking at least twice the recommended serving and often 3x that. I had a bowl that was like a large pasta serving bowl for a few people to serve from. I filled it with porridge and honey before a long walk then wondered why I had to eat most of my lunch by 10-11am. I personally feel the honey added to porridge has something to do with it going straight through your system and you run out of energy quickly. Never tried it but suspect fruit and porridge might work better. I think fruit sugars trigger less of a sugar/insulin response but i am guessing here.

Whatever you do, I think you need to control the high sugar levels. Eat little and often. Reduce the energy bars/gels, increase the more natural but fast intake foods. Bananas are well known food for people exercising., Easy to absorb and depending on the level of ripeness can be very high sugars or lower sugars. If it is hard and not that ripe it has higher starches which are slower intake I think. Eat it black and gooey it is very high in sugars (and like over-ripe kiwi fruit can have the hint of an alcohol taste too). I know gels are easier to carry but it sounds like you are one of potentially the minority who they don't work for. I'm like that.

The above are just my experience and problems I had when exercising for longer times. Hope they help.

Harrogate Velo50

Ta v much for the replies so far guy's, appreciate you taking the time.

Tangled Metal, thanks again. I very rarely take a gel, only have one if last resort to get something into me quickly, and then I reckon only take them if a ride over 50 miles and am desperate!

Porridge thing is interesting as I never used to like it much, but people seem to think it's the thing, so have given it a go with some nuts, dried fruit and bit of honey and while I like it now, can't say as it has made me feel better on the ride

tangled_metal

Perhaps ditch the porridge for something else. IMHO porridge is for those who are not exercising much as a healthy breakfast food. I don't find it a good start for an active day myself. We are all different so it will work for some. Personally I struggle even eating anything first thing in the morning anyway. Porridge just feels like too much hard work to eat it and keep it down. At most toast and butter with a wholemeal cereal like Weetabix or shredded wheat for me. Basically wholemeal carbs with a bit of fats in the butter and if I have time a hardboiled egg.

Drinks could be orange mixed with water and a tiny pinch of salt if it is hot and you are sweating badly. That is as good as you need for an isotonic drink plus you can tailor it to be hypo or hyper tonic (let me get this right, the former is when there is less sugars and salts and the latter is where there are more salts and sugars in it so it goes into the blood slower but gives you a bit more energy). There is even a company that sells special spoons that you use to measure out the correct mix of salt and sugar to add to a volume of water to make the optimum strength isotonic drink for hydration purposes. Can't remember the name but its a cheaper way to make a drink up thank buying them.

timmys7

Have you eaten well the day before these rides, brown bread,pasta etc? This is your fuel for your ride.

Diamant49

Porridge works for me, either before a ride (but at least two - three hours before), or immediately afterwards - but I do agree that it has been over presented as a slow release carb (low GI). As with all the GI stuff it depends on a lot of factors, such as the type of oats used (steel cut, not rolled or part cooked); how long its soaked/cooked for (longer = quicker effect); what its cooked with - full-fat milk slows down carb release more than water; what its eaten with - fruit and nuts will also slow down release. And thats before you consider individual metabolism!

A point about insulin release though - people often talk about gels etc taken during exercise as causing an insulin spike, with a crash in blood sugar. This is highly unlikely, as the body does not require insulin to move glucose across cell membranes during exercise, and releases very little "background" insulin either (I am diabetic, so on a moderately intense ride over 90 mins I take no insulin with food, have little or no background insulin - and eating sensibly, including gels if necessary, I will not increase my blood sugar levels, just keep them stable - if I guess correctly!). So feeling good after eating a gel/bar, whatever and then having a knock is more likely either fatigue or not actually eating enough?

The mistake that can be made, I think, is taking too much fast-acting carbs too early, or just before exercise - the insulin production by the body is wound down as exercise progresses, so if too much is eaten at this stage then too much insulin maybe could be released and cause a drop in blood sugars?

For the OP, you do look to have fuelled ok - but you could be suffering from glycogen depletion due to activity on previous days and not fuelling enough following that? It takes time for glycogen reserves to be restored (depends on person, diet, activity etc.) - could be up to 48 hours after previous activity. Fuelling needs to be considered in this context, not just on the individual ride.

Harrogate Velo50

Diamant49 wrote:

Porridge works for me, either before a ride (but at least two - three hours before), or immediately afterwards - but I do agree that it has been over presented as a slow release carb (low GI). As with all the GI stuff it depends on a lot of factors, such as the type of oats used (steel cut, not rolled or part cooked); how long its soaked/cooked for (longer = quicker effect); what its cooked with - full-fat milk slows down carb release more than water; what its eaten with - fruit and nuts will also slow down release. And thats before you consider individual metabolism!

A point about insulin release though - people often talk about gels etc taken during exercise as causing an insulin spike, with a crash in blood sugar. This is highly unlikely, as the body does not require insulin to move glucose across cell membranes during exercise, and releases very little "background" insulin either (I am diabetic, so on a moderately intense ride over 90 mins I take no insulin with food, have little or no background insulin - and eating sensibly, including gels if necessary, I will not increase my blood sugar levels, just keep them stable - if I guess correctly!). So feeling good after eating a gel/bar, whatever and then having a knock is more likely either fatigue or not actually eating enough?

The mistake that can be made, I think, is taking too much fast-acting carbs too early, or just before exercise - the insulin production by the body is wound down as exercise progresses, so if too much is eaten at this stage then too much insulin maybe could be released and cause a drop in blood sugars?

For the OP, you do look to have fuelled ok - but you could be suffering from glycogen depletion due to activity on previous days and not fuelling enough following that? It takes time for glycogen reserves to be restored (depends on person, diet, activity etc.) - could be up to 48 hours after previous activity. Fuelling needs to be considered in this context, not just on the individual ride.

Thanks for that. Interesting.

Think you may have hit nail on head with glycogen depletion (how can I fix this?) Due to activity on previous days as I did a fairly tough turbo session two days before, but thought I was ok.

I think I fuelled ok day before as had pasta and sweet potatoes night before the 79miler, tend not to over think my diet day before a short steady ride of 40 or so, maybe I should!

Diamant49

Funny enough I did a tough turbo session on Monday morning - FTP test, and nothing until this morning - then I did a fairly easy endurance session and although I had a banana to eat before I started and reduced basal insulin by 50%, I still had to take a gel within the first 30 minutes. I was really shaky, but was fine again in a few minutes and had a good workout (with normal blood sugar at the end), but I rarely need to eat that much so early on.

The key is probably intensity rather than duration - a hard session on the turbo can use a much higher proportion of glycogen as fuel than a longer, less intense session on the road (I find it hard to do an easy turbo session - boredom kicks in very quickly).

In tmy case I will probably have a bowl of cereal (shreddies with natural yoghurt and stewed apple) tonight at bedtime, as I want to do another session tomorrow morning. I don't usually like eating late at night, but I find its a good way of getting some additional carbs in before another session, and leaving the body to assimilate it as needed.

tangled_metal

My guess is the intensity is important too. My understanding of intensity and glycogen depletion is based on the mix of energy from fats and sugars. As intensity goes up the body can not get enough energy from the fats fast enough so moves more into sugar useage.

I must say I am a complete lay person who has kind of remembered snippets of information and has a certain mix of experiences so I am likely to be wrong. For me diet is very important aspect. I am not diabetic but diet impacts in other health conditions so I am acutely aware of the need to eat regularly. I am not a very good practitioner of eating a little and often but I tend to eat a lot at the evening meal then nothing until lunch. A few months back (April/May) I started commuting into work again. Not far but being unfit it took more out of me than it used to. I found on the first day that I ran out of energy about 3pm. I then started trying to eat breakfast but could not do it. I ended up preparing a decent pasta based lunch and eating a banana 15 minutes before riding home. That solved my hitting the wall energy wise.

At the end of the day it is purely a case of balancing what goes in against what is required by you body. On top of that you have to consider what suits you. Porridge is one of those "marmite" foods as far as I am concerned. It does not suit me. I have also found oatibix doesn;'t but weetabix does. Now they are basically the same except one is oats the other is wheat. I find that interesting but not sure relevent to anyone but me.

bahzob

You can do a rough and ready calculation of how many calories you burn on a ride and so whether or not nutrition is a key factor

This site will give power in watts needed for a given speed http://bikecalculator.com/index.html

KJ then = watts * ride time in seconds / 1000.

KJ = roughly kcal since 1 kcal = 4 kj but the body is only roughly 25% efficient converting food to bike power (rest goes off as heat)

The bike calculator shows this at the bottom (though it uses a slightly different efficiency calculation)

These kcal come from 3 sources, carbohydrate, fat and protein. The balance between the 3 varies according to how intense the ride is. At threshold it will be 95% carbs, very easy 95% fat. Anywhere in between will vary with individual and their fitness. Indeed one objective of endurance training is to improve the fat%. Finding out your precise value requires a lab test e.g. http://www.dcrainmaker.com/2012/01/look-at-testing-with-new-leaf-fitness.html

But as a rough rule of thumb at endurance pace 50% of calories come from carbohydrate.

So taking 70 mile flat ride at say an average of 15 mph on a perfect course

Bike calculator guesses that this requires 110W = 1760 calories or so.

If 50% of this comes from carbs then you shouldn't bonk as, assuming you are rested, you have enough glycogen for 1600kcal or so work.

Playing around with the calculator then for a 70 mile ride in the same conditions 20mph or a 5 mph headwind starts to move you into danger territory as it now requires 2700 cals and a greater proportion of this will come from carbs since you are working harder.

None of this is of course gospel. But it is a bit of fun and can give an insight as to whether you under ate for a ride or had a problem due to some other issue.